Stencil printing machine



Dec. 25, 1951 A. c. BARLOW EI'AL STENCIL PRINTING MACHINE 5 Sheets-Sheet 1 Filed Sept. 4, 1945 F0 0m 5 ON Wm Y .mA m Wm E w WSM 5. ML LE \v w I B Dec. 25, 1951 A. c. BARLOW ETAL 2,579,461

STENCIL PRINTING MACHINE Filed Sept. 4, 1945 5 Sheets-Sheet 2 fl'g E 3o INVENTOR.

A TTUENEY Dec. 25, 1951 A. c. BARLOW ETAL.

STENCIL PRINTING MACHINE 5 Sheets-Sheet 3 Filed Sept. 4, 1945 INVENTOR. .ALMUS E, EA ELEIW ZOI WILLIAM H FA UL Dec. 25, 1951 A, c, BARLOW TA 2,579,461

STENCIL PRINTING MACHINE Filed Sept. 4, 1945 5 Sheets-Sheet 4 WJ w -27l W 269 W INVENTOR. .ALMUS C. EAELDW' Y WILLIAM TZFAUL A TUHNEY' Patented Dec. 25, 1951 STENCIL PRINTING MACHINE Minus 0. Barlow, Ghula Vista, and William V.

; Paul, Coronado, Calif.

Application September 4, 1945, Serial N 0. 614,336

(Granted under the act of March 3, 1883, as amended April 30, 1928'; 370 0. G. 757) 13 Claims.

This invention relatesto printing machines and more particularly to those of the silk screen type wherein an impression is made upon a work piece by passing paint, ink; or the like through a stencilled pattern of the screen onto a work piece arranged below the screen.

It has heretofore been the practice in this art to hinge a screen on a bed frame; lift the screen; place a work piece to be printed on the bed frame; lower the screen; apply paint onthe screen; impress the paint on the workpiece by drawing the paint with a manually operated squeegee over the screen. to force it through a stencil; lifting the screen; and manually removing the so printed work piece. These briefly outlined steps in the conventional silk screen process of printing are slow, tedious and leave much to be desired inthe quality of work that can be produced. 7

The principal objects of the present invention are therefore, to provide a printing machine of the silk screen type that is semi-automatic; that has many times the productive capacity of machines heretofore available for the same purpose; and that greatly improves the quality cfwork accomplished.

Other objects of this invention are to provide for moving the work piece and screen relative to a printing element called. asqueegee instead of moving the squeegee over the screen as has heretofore been the practice to provide for making off-contact" prints resulting in sharper, clearer, more perfect images than has heretofore been possible; and to reduce the size of printing surfaces in the machine, yet provide an end.- less printing base.

Other objects of thelnvention are to provide improved elements and arrangements thereof in a machine of this character; and to accomplish thenoted objects in a facile, relatively economical and highly efficient manner.

In accomplishing these and other objects of the present invention,. we have provided improved details of structure, the preferred form of which is illustrated in the accompanying drawings, wherein:

Fig. 1. is a perspective view of my improved printing machine showing the general assembly.

Fig. 2 is a detail perspective view of the work piece feed trays Fig. 3 is a detail perspective view of the mechanism for forwarding workpieces from the feed tray to the conveyor assembly.

operative platen printing base and squeegee Fig. 7 is a diagrammatic top plan view of the synchronized drive system for the conveyors, platen, feed and delivery mechanisms.

Fig. 8 is a detail side elevational view of a portion of the machine chassis having the piston valves for timing the vacuum lines to the feed and stripping mechanisms.

Fig. 9 is a detail perspective view of the work piece gripping and stripping mechanisms and the delivery end of our improved printing machine.

Fig. 10 is a vdetail sectional view of the work piece gripping and stripping mechanism.

Referring more in detail to the drawing:

In Fig. l, the general assembly of my printing machine is shown, wherein l designates the main chassis or frame; 2', the feed tray; 35, the feed mechanism; l, the ejector mechanism su port; 5, the squeegee assembly; 6, the silk screen frame with gripping mechanism attached; '5, the screen frame oscillating mechanism; and e, the work piece stripping and delivery mechanisms.

The chassis InFig. 1 is shown the chassis I, which preferably comprises upright side and/or end legs Ill and II, the lower ends of which are braced by stringers l2 and I3 and end plates Ill. The upper ends of the legs l0 and II are inter-connected and braced by side rails l5 and I6 and by suitably arranged transverse bracing members. Outriggers I? and [8' extend outwardly from the end l0 of the chassis, the Outriggers being suitably mounted and based on the chassis and being connected by a yoke It at the outer ends. 2| extend outwardly from the opposite end [I of the chassis, these latter outriggers being suitably inter-connected braced and mounted on the chassis in approximately the plane of the rails l5 and I6 and the Outriggers I l and it.

Arranged transversely of the outriggers I! and it in outwardly spaced relation to the end it of the chassis is a supporting block 22 on which is mounted a guide fili'gel' support 2?. Substantially similar finger supports are mounted on or adjacent the outriggers W and is. End guide fingers 2E as well as side guide fingers 2'5 depend from such finger supports a distance sufficient to accommodate and guide an adequate supply of stock to be printed for a substantial printing jobJ e A sprocket 25' is rotatably mounted on the outrigger IT on the exterior face thereof which is driven by a pinion 21 also rotatably mounted on the outer face of the outrigger ll which pinion is in turn provided with a handle 2'8 for driving the same and transmitting motion to a shaft 29 supporting the sprocket 26. The shaft ZB'ext'end's transversely between the riggers H and I8- and is suitably rotatably mountedtherebetween.

oppositely arranged outriggers 2t and The feed tray As more clearly shown in Fig.2, the sprocket shaft 29 for the pinion driven sprocket 26 is provided with bevel gears 33 adjacent its ends which gears mesh in driving relation to bevel gears 3|. on shafts 32 that are arranged perpendicularly to the shaft 29 and extend outwardly from the chassis. shafts 32 drivingly engage bevel gears .34 on the upper ends of vertically arranged shafts 35. The shafts 34 are rotatably mounted in brackets 35, Fig. 1, that are suitably mounted on and depend from the riggers i! and l8 in oppositely disposed relation.

The shafts 35 are threaded, as indicated at 31, such threads being arranged to mate with threads in collars 38 in such a manner that rotation of the shafts "moves the collars up and down the shafts in accordance with direction of rotation of the shafts. The collars 38 are provided with brackets 38 upon which a bed plate 45 is mounted for supporting a quantity of work pieces (not shown) such as sheets of paper, felt, metal, tile, glass, linoleum, ply board and the like between the end and side guide fingers.

It will be apparent that a supply of workpieces may be placed on the bed plate 40 and that such work pieces will be held in desired position by the guide fingers 24 and 25. Actuation of the handle 28 transmits motion to the bed plate 43 through the shafts, gears and threads to raise the plate and feed the work pieces.

The feed mechanism We have devised an arrangement for moving individual work pieces from the top of the stack on the bed plate 40, the details of which are Bevel gears 33 on the outer ends of shown in Figure 3. This mechanism preferably consists of a series of suction cups 4| designed to engage the upper surface of successively presented work pieces. The suction cups 4! are operatively connected with the lines 42 leading to a source of reduced pressure or a partial vacuum by way of a manifold 43. provided with a pressure regulating valve 44 interposed between the manifold and the vacuum line 45.

The manifold 43 is The line 45, as shown in Fig. 1, extends from 4 v the manifold to the lower left hand portion of the chassis where it connects, as at 46, with a vacuum pump 41. The pump 41 is preferably of the oil seal type and is driven through the power take-01f 48 of an electric motor 49. The pump and motor are suitably supported on a bed plate 5 53 arranged transversely on the upper edges of the stringers l2 and [3, while the electric current for the motor 49 comes through the leads 5| of a control box 52 that is suitably mounted on the legs H and rail l6.

As clearly shown in Fig. 3, the manifold 43 is supported by a pair of vertically arranged rods 53 (Fig. 1) which in turn, are each supported by a riser bracket 54.

In order to make the suction cups 4| adjust- 'It being apparent that the suction cups pick up the uppermost' work-pieces in'a stack on the bed plate 40, we have provided for moving the suction cups forwardly in a circular and reciprocating motion in such a manner that the work pieces may be fed to be printed and the suction cups returned to engage succeeding work pieces. In'carrying out this function of the device, the riser bracket 54 is mounted on a floating bar 60. The outer end SI of the bar 50 is vertically reciprocable in the guide bracket 52 and the opposite inner end thereof is swivelled, as at 63, in a yoke 54 that is swivelly mounted on the outrigger 58, as indicated at 65. Vertical movement of the end GI of the float bar 33 is limited by a set screw 66 inthe bracket 62 to accommodate vertical lift of the suction cup to stacks of Work pieces of different thicknesses.

"The float bar 60 is moved synchronously with actuation of the printing machine by the following arrangement: 6'! designates a head on the riser bracket 54 to which a link 68 is pivoted, as indicated at 69. The other end of the link 68 is pivotally mounted, as at 70, on an arm H that is fixed to a cam shaft 18, the shaft 18 being rotatab-ly mounted in the outrigger I53, as more clearly shown in Fig. 7. A cam 19 is mounted on the shaft 18 and has a low lobe portion 83 on its periphery that is followed by a cam follower 8| on an arm 82, which latter arm is fixed to the float bar 63. The cam shaft #8 is driven by a chain or belt 83,v the inner run of which is mounted on and driven by a sprocket or pulley 84, mounted on a line counter shaft 85 arranged transversely between the side rails and outriggers and having rotatable bearing support thereon, as at 86.

It is thus apparent that as the line shaft 85 rotates, its motion is transferred to the cam 19 for alternately lifting and lowering the float bar Gil. At the same time, the arm ii on the cam shaft causes the link 68 to move the riser bracket 54 in a substantially horizontal reciprocating motion. This in turn causes the suction cups to lift work pieces and move them forwardly.

In order to release the work pieces, the vacuum in the line 45-46 to the vacuum pump 41 should be cut-off at or just prior to the extremity of movement of the suction cup 4| to the left in Fig. 3 and to this end a cam 8? is arranged on the line counter shaft .85. The cam 81 is provided with lobe portions related to the lobe portions of the cam 19, which act on the springpressed plunger 88 of a piston type valve 89 that is supported as by a bracket 90 "on the outrigger l8 in interposed relation in the vacuum line 45-46 for cutting-off the reduced pressure in the line and allowing atmospheric pressure on the work pieces to remove the same from the suction cups. Thereafter, the suction cups may be moved backwardly'toward the work piece bed plate to engage and move succeeding work pieces.

The ejector mechanism '94 that is also rotatably mounted on the bracket 9|. The gear 94 is adapted to be driven by a gear 95 that is mounted on the end of a shaft 93 adjacent thereto. The shaft 96 is also shown in Fig. 7 and is rotatably supported at its ends in the Outriggers 11 and I8" in such a manner as to the belts 98 travel in such a manner as not to interfere with an upper feed roller I03 which latter roller is cooperative with the feed roller 92 to meter the feed of work pieces to the printing machine.

The'upper feed roller I03 is adjustable vertically by means of blocks I04 that are adjustably mounted in ways I05 in the brackets SH and which blocks rotatably support reduced ends of the roller I03. The feed roller I03 is full-floating and operates against an adjustment spring I06, the lower end of which bears against the block I04 and the upper end of which is mounted on and bears against a boss i 01 that is fitted within the ways I05 and onto the lower end of an adjustment screw I08.

The reduced end, Fig. 4, of the upper feed roller I03 reacts against a follower roller I09 that is rotatably mounted upon a bar H0, fulcrummed, as at I I I, on the bracket 9 I. The end of the bar IIO opposite the roller I 09 is fixed, as at H2, to a supporting block H3, the block I I3 being pivotally supported on and by the pivot bar H4. The outer ends of the pivot bar 5 I4 are mounted in arm extensions I I5, the opposite ends of which are fixed to arms I I9, Fig. 1, that extend upwardly from the brackets 9 I.

p The blocks I I3" pivotally support an ejector tray II1 by means of a downwardly turned lip H8 or the like that may be secured to the block He by a pin II9. The tray H1 is of such a length and width that it traverses the path of work pieces fed to the rollers 92 and I03 by the feeding mechanism, Fig. 3, and is preferably provided with slots, notches or recesses I20 which fit over and pass the conveyor belts 98 to fall below the point of clearance between the rollers 92 and I93 at the conveyor belts 98. The ejector tray I I1 is finely counterbalanced by weights I2I that are adjustably mounted on the counterbalance bars I22 that project inwardly relative to the machine from the tray supporting blocks. I I3.

In order to adjust the ejector tray for ejection of relatively rigid material, adjustment screws I23 and I24 are provided on an ejector tray supporting plate I25, such screws I23 and I24 being adapted to bear against an adjustment plate Hi5 fixed on each of the blocks H3 to pivot the ejector tray II1 angularly relative to the plate I26.

It is thus apparent that the ejector tray ii? may be adjusted to fine tolerances for passing work pieces of desired thickness below the ejector tray, below the feed roller I03, on top of the conveyor belts 98 and on top of the feed roller 92. Thus, when work pieces of greater thickness than desired, or when a plurality of work pieces, are accidentally fed to the conveyor belts 98, such additional thickness of material raises. the floating roller I03 to fulcrum the bearing roller E09 upwardly on the. fulcrum III which, through the other end of the bar at II2, lowers the ejector tray 1 to drop the notched end I20 of the ejector tray over the conveyor belts 98 to pick up the undesired work piece or a plurality thereof and thus avoid. feeding the printing machine. improperly.

.6. The squeegee assembly Once each work piece has 'been'delivered by the feed mechanism and haspassed the ejector tray, the conveyor belts 98, Fig.5, pass each work piece to a platen I21, Fig.5, which platen provides an endless printing base giving a substantially point contact by which substantially oficontactprints are made upon the work pieces as later more fully described.

The platen I21 is vertically adjustable along with the supporting shafts I 0| and. I28, Fig. 7, for the inner runs 99 and I29 of the conveyor belts, by means of bearing brackets I30, Fig. 5, which brackets have adjusting slots I3I through which bolts I32 pass for engagement in the side rails I5 and I9, Fig. 7. I

The brackets I 30 are also provided with ways I34 in which arms I35 and I36 areslidably adjustably mounted, as by bolts I31. Roller bearings I39 on the "brackets I30 support the ends of the platen. Roller bearings I39 and I40 support the ends of the conveyor belt shafts IOI and I28, respectively.

While the screen per se is superimposed on each work piece at the time the work piece passes over the platen I21, such screen and frame therefor are co-related with the stripping and delivery mechanisms of the printing machine and will for that reason be described later herein.

In Figs. 1 and 5, MI designates a yoke for the squeegee or printing element of this printing machine. The yoke MI is mounted at its ends I42 on the upper ends of supporting posts I43 and I44, the lower ends of which have bases I45 that are mounted on the side rails I5 and I0 of the main chassis, as by the bolts illustrated.

The posts I43 and I44 are slotted longitudinally, as particularly shown at I45, Fig. 1, to slidably receivea squeegee supporting bar or yoke I41, the outer ends of which are arranged exteriorly of the side rails I5 and I0 and the inner web or head portion I48 of which is arranged interiorly of said posts below the yoke I In order to allow controlled vertical reciprocation of the squeegee yoke I48 in the slotted ways of the posts I43 and I44, latching dogs I49 are pivoted to the side rails I5 and I9, as shown at. l50, Fig. l. The upper ends of the dogs I49 are secured to an operating arm I'5I that may be suitably operated and in this instance is adapted for manual operation or reciprocation in a horizontal plane in slidably supported relation to the upper ends of the rails I5 and I6.

The supporting bar web I40 is adapted to removably receive a squeegee unit consisting of a head yoke I52 adapted to slidably fit within the yoke I41 and having bearing surfaces I53 against which latching dogs i554 may be turned to bear against and hold the squeegee unit I52 in the supporting bar I41. Mounted on and supported by the. squeegee unit head yoke I52 are oppositely arranged bearing blocks I55 that support therebetween a preferably cast channel I56 for receiving an elongated block (not shown) within its interior. The lower end of the channel is longitudinally slotted to receive a conventional rubber squeegee strip I51 by which printing material may be spread upon a work piece therebeheath. Headed screws I58. and I59 are screwed into the block just referred to, to hold the block and squeegee within and relative to the channel I50. Set screws I60and IBI are mounted in and extend through the channel I56 to bear against the block and adjust the same laterally in a de- 7 2 sired manner to insure a uniform application of printing material to the work piece.

It is sometimes desirable to adjust the squeegee longitudinally relative to a work piece and the printing machine and to this end the blocks I are journaled to receive a transverse shaft I62, the left hand side of which, Fig. 5, is provided with a pinion I63.- The shaft I62 extends outwardly toward the left, Fig. 5, and terminates in a handle portion I64 by which the pinion I63 may be turned in either direction. The pinion I63 acts on a gear I that is mounted on a shaft I66 supported at its ends in journals in the blocks I55. The shaft I66 is additionally provided with gears I61 and IE8 that mesh in driving engagement with racks I69 to adjust the squeegee supporting casting angularly longitudinally relative to a work piece.

Mounted on the squeegee unit head I52 is a boss I10 in which a stem I1I, Fig. 1, is arranged, which stem extends upwardly through the main supporting yoke I4I and is provided with threads engageable with threads in a passage through the yoke MI by which the limit of reciprocation of the head or bar I48 in the posts I43 and I44 may be adjusted by turning the handle I12 to effect the desired adjustment. A spring I13 on the stem III bears against the boss I10 and an oppositely disposed bearing boss I14 to resiliently cushion the head I48 during its vertical reciprocation.

Extending laterally from the yoke MI 'is' a flange I15 that supports one end I16 of an arm I11, the other end of which is provided with a yoke to pivotally mount, as at I18, a connecting rod I19 to which is attached a paint trap I80, the lower edge of which is adapted to depend below and cover the printing edge of the squeegee I51. The trap I is pivotally connected to the connecting rod I19, as at I8I and is additionally pivotally connected at its ends adjacent its lower edge by pivoting links to the squeegee channel.

It will thus be apparent that the connecting rod I19 being in fixed relation to the yoke I4I at its upper end and in pivotal relation to the squeegee I51 at its lower end, as the squeegee is raised, the paint trap I80 is pivoted and drawn over the squeegee in a downward direction and to the left relative to Fig. 1. As the squeegeeis lowered, the upper end of the paint 'trap connecting rod remaining fixed, the lower pivoted links of the paint trap push the paint trap upwardly to'the right to allow paint therein to contact the squeegee and thus allow the squeegee to spread the paint.

In order to supply the paint trap I80 with a supply of painting material, a bucket I82 is 'provided, which is preferably mounted on the yoke I4I, as by the strap bracket I83, mounted on the yoke. The bucket has an outlet line I84 that may be controlled by a valve I85 to admit desired amounts of painting material to a line I86 that leads to the paint trap I80.

In order to vertically reciprocate the squeegee yoke I48, the lower ends of the arms I41 of such unit are provided with cam followers I81, 1, adapted to ride upon the peripheries of cams I88, which cams are mounted on the outer ends of the main. drive shaft I85. As shown in Fig. 7,

the main drive shaft is driven by a'sprocket connected by a belt or chain I90 with a sprocket on a stub shaft IQI. The stub shaft is connected to and supported by the main drive shaft by a knee joint I92. Also mounted on the stub shaft I9I is a sprocket which has a belt or chain I93 that leads downwardly toasprocket I94 on a drive shaft I95 of'a gear box I96, Fig. 1. The gear box. I96 is connected by a clutched driven shaft I91 with the drive shaft of an electric motor I98 that has leads I99 connected with a control box 200 that is suitably supported on the chassis. for example on the end members I0, as shown in Fig. 1. V I

It is thus apparent thatenergization of the motor I98 and consequent actuation of gear box I96 rotates the sprocket I94 and, through the chain or belt I93, transmits rotary motion to the main drive shaft through the chain or belt I90. Rotation of the main drive shaft I89 turns the cams I88 to raise or lower the squeegee unit depending upon the position of high or low lobe portions of the cams relative to the cam followers I81 on the squeegee unit.

The screen frameand oscillating mechanisms As shown in Figs. 1 and 5, the side rails I5 and I6 are provided with Ways 26! that are arranged to slidably reciprocably receive the side rails 202 of a silk screen supporting frame 203. The side rails of the frame are connected by end members 204, Fig. 5, and 295, Fig. 9. The screen frame is further provided with seat 206 and 281, Fig. 5, along the inside bottom edges of the side rails thereof on which a wooden or like frame may be removably mounted as by suitable wedges known in the art.

It is customary in the practice to tack or otherwise secure a silk screen having a suitable stencil to such a wood frame and in this instance the frame may be respectively provided with a plurality of screens having various suitable stencils depending upon the work to be done. 7

In order to reciprocate the frame 283m the ways 25H and thus cause a silk screen on the frame to be moved relative to the squeegee printing element, the frame 283 is provided with links or lugs 208, Fig. 9, the links or lugs 268 being connected to the upper ends of rocker arms 203. The lower ends of the arms 209 are fixed to a shaft 2I8, Fig. 1, that is rotatably supported in bearings 2| I or blocks that preferably form a part of and extend upwardly from the chassis stringers I2 and I3. Also fixed on the shaft 2 I0 and preferably arranged inwardly relative to the arms 209 are complementary rocker arms 2I2 that extend at an angle to the arms 209 and have slots 2I3 in which the crank pins of pitmans 2I4 engage. The pitmans 2 I4 are mounted on the drive shaft I95 of the gear box I95 and rotate to throw the arms 2I2 in an up and down direction to pivot the arms 209 and reciprocate the screen frame 203 in a horizontal direction in its ways 2!.

In some instances, it is desirable to adjust the length of stroke of the screen frame 203 depending upon the size of work pieces to be printed. The length of stroke of the frame 284 is adjusted by adjusting the position of the pitman crank pins relative to the length of the rocker throw arms 2I2.

In accomplishing this adjustment, the gear box I96 is provided with a base 2I5, the ends of which are slidably mounted in tracks 2I6 on the interior faces of the stringers I2 and I3. At one end of the gear box base 2I5 a rack gear 2I1 is mounted that also slides in one of the tracks 2I6 and engages a sprocket 2I8 that is mounted on a shaft H9. The sprocket 2I8 engages a pinion 220 on a shaft 22I rotatably supported by a bearing block 222. The shaft 22I rotatably supports another sprocket 223 to which-a.

cooperative gear rack 2ll to move the gear box base 2|5 along the-stringers I 2 and i3 in the corresponding direction of-rotati-on of the handle .As the gear box is, moved to the left, Fig. 1, rotation of the pitmans 2l4 reciprocates the rockor throw arms 259- in sucha manner as to approach their extreme; limit of throw; that is to.

say, maximum movement vof the rocker throw arms 2&9 obtained by movingthe gear box to the left, Fig-1, whereas'minimum throw of the arms -9: is obtained by movement of the gear box to the rightrelative to Fig; 1. Increase and decrease in the length of stroke of the screen frame 204 is accordingly provided for relative to the squeegee with which is ooacts.

The work piece gripping mechanism When the silk screen frame 233 moves to the rightrelative to Fig. l, the. machine is designed to feed work pieces to the. left from the feed tray, also relative-to Fig. 1. The screen frame should begand is. therefore, provided with an arrangement for gripping the work .Dieces and holding them in registry with the frame in a manner now to be described. Y

The screen frame as heretofore indicated is provided with the end bar;205, Figs. 9 and 19,

which has associated therewith a channel or r.

chamber 205a, the bottom surface of which is provided with an inwardly directed lateral extension plate 229, Figs. 1 and 10, the rear bottom 'edge'oi which is provided with stops 235, Figs. 9 and 10, against which the ends of the work pieces abut. The member 255 is hollow and is perforated at its lower surface to provide suction openings 2051) by which an imposed vacuum may act on the upper surface of the work pieces to hold the same in registry-with the frame. The upper surface of the chamber 295a is also perforated to receive tubes 23! leading to a manifold 232 which in turn is provided with a vacuum line 233 which connects as at 234 with the vacuum pump 41, Fig. 1. The 'manifo1d232 has brackets 235 at its ends, which brackets are resiliently supported by stems 235 and springs 231. on bearing blocks 238 that are mounted; as by bolts,

, on the frame end member 205.

Should the workpieces be out of registrywith the stops 230, they will expose the vacuum line openings 2415b ,and insufficientv vacuum will be applied to hold the work pieces in place. It is contemplated that such. deficiency may be employed to advantage by causing a shut-off of the electrical system and stopping. of the machine to prevent improper printing of work pieces.

Cooperative with the suction chamber 295a in holding work pieces in registry with the frame are gripping fingers 239 the end of each of which is fixed to a gripping finger bar 240, having ends mounted on grip finger bar forks 24| The forks 24l are mounted at their upper ends on a fork shaft 242 andthe shaft 242 is provided with cam 10 shaft brackets 243, at, its ends for mounting said shaft 242 relative to a push rod his shaft 244. The grip fingers 239, are positioned on the. bar 245. in such a manner as to engage a work piece abutting the stop lugs 235, when in the position shown in Fig. 9. The arrangement is such that the noted position is maintained throughout the length of stroke of, the silk screen frame. As the frame approaches the end of its stroke, that is in ajd-irection to the left relative to Fig. 1, spring loaded release means or push rods 245 that are mounted in the chamber 205a in alignment with the grip fingers- 239, are forced downwardly, Figs. 5!: and 10. by the ends of push rod lugs 246 on the shaft 2.44... This action of the lugs and rods forces the work, piece away from the vacuum chamber 255w and displaces the work piece from its engagement with the stop lugs 23D.

' Simultaneously with downward movement of the. release means or push rods 245, the grip fingers 232 are moved to the left relative to Fig. 1 by movement. of, the grip f nger bar 242 by means of a fork shaft cam bracket 241. The bracket 24! is provided with a follower 248 that rides on a floating bar 249. The outer end of the floating; bar 249 is pivoted to a yoke 250 which in turn is pivoted to a mounting bracket. 25! suitably secured to the side rail [5. The other end f. the. bar 249 is pivoted to a yoke 252 which in turn is. piv tallv mounted on the. conveyor belt shaft [2 It. is. apparent. theref re. that. inward. move..- r'nent of the bar 249 on its yokes. that. is to the right relative to. Fig... z raises he bar 249 throu h out its l n th. appr ximat ly in the sam plane whereupon the follower 248' riding on the bar 24.3, pivots the fork shaft. cam bracket; 241 upwardly and outwardly in an arc to rotate the shaft 24;.2 and cause the grip fingers 239 to move outwardly relative to the chamber 205a, thus tending to draw the work pieces out from under the silk screen frame.

The push rod lug shaft 244 is provided at an outer end thereof with an arm 253 that sup ports at its lower end a follower 253a. The follower 253a rides on another floating arm 254 that is pivoted at one end to a yoke 255 and at its other end to a yoke 256 on the conveyor belt shaft I23. It is apparent here also that inward pivotal movement of the yokes 255 and 255 raises the arm 254 and consequently raises the follower 253a to pivot the arm 253 outwardly and upwardly. This movement of the arm 253 rotates the shaft 244 and forces the lugs 245 downwardly to depress the spring loaded release means or rods 245. The rods 245 then engage the upper surface of a work piece to force it downwardly out of registry with the stop lugs 235 and thus cooperate with the grip fingers 2.39 to-remove the work pieces from the silk screen frame.

. In order to provide for pivoting the yokes and thus raising the floating bars, 249 and 254 to move the grip finger and pusher lug shafts, the ends of the arms 249 and 254 are extended to formbearing pieces. 25'! and 25 Y The arm d 25? is engageable by one end 259. of a lever 26%! that-is fixed to. a shaft 2Bl rotatably mounted in supporting brackets 262 and 25s that are adjustably mounted in and depend from the side rails l5 and 15. The other end 264 of the lever 2% has a follower 265 that rides the periphery of a cam 266 that is mounted on a shaft 261 rotatably driven by a sprocket or pulley 268 and 1 1 a chain or belt 269, the chain 269 leading to a sprocket on the stub shaft I9I, Fig. 7.

219 designates a bearing rotatably mounted on the grip finger shaft 261 for supporting one end of a knee joint 2'II, the other end of which is mounted in a bearing 212 on the stub shaft I9I, Fig. '1.

The end 258 of the floating arm 254 is adapted to be engaged by the end 213 of a lever 214, the opposite end of which is provided with a follower 215 that rides on a cam 216 which is also mounted on the grip finger shaft 261.

It is thus apparent that as the grip finger shaft 261 rotates, the high and low lobe portions of the cams 266 and 216 cause the cam followers of the levers 269 and 214 to alternately push the yokes 259 and 255 inwardly and upwardly and then let them return to downward position by gravity to thus effect rotation of the bars 242 and 244 through the arms 241 and 252 to actuate the grip fingers 239 and pusher rods 245.

The delivery mechanism The grip finger assembly is full floating and gradually recedes below the top level of the silk screen frame 293 as the frame travels to the extreme of its stroke, that is to the left relative to Fig. 1. This receding action strips pliable materials being processed from the silk screen where viscous materials tends to hold the work to the silk screen. The depth to which the grip finger assembly recedes is adjusted by raising or lowering a retractor lug bar 211 together with the cam assembly associated with the finger grip and cam shaft 261 as well as the conveyor belt assembly in a manner now to be described.

The lug bar 211 is pivoted at its outer end to the bracket 262 and at its inner end is pivoted to the side rail I5, as indicated at 218. Outwardly extending bracket flanges 219 and 289 are provided on the brackets 262 and 263, the flanges being provided with openings for the passage of threaded adjustable rods 28I and 282. The lower ends of the rods 28I and 282 are provided with level gears 283 and 284 which cooperatively respectively engage bevel gears 285 and 286 on a shaft 281 rotatably supported in brackets 288 and 289 that form extensions of the brackets 262 and 263. The shaft 281 is provided with an operating handle 299 turning of which moves the adjusting rods 28I and 282 upwardly or downwardly relative to threaded apertures in substantially U-shaped brackets 29I and 292 that are vertically mounted in the side rails I and I6, respectively.

It is thus apparent that the handle 299 may be turned in desired direction to raise or lower the retractor lug bar 211 as well as the gripper shaft and cam shaft assemblies It is also desirable to adjust the conveyor belt assembly in substantially corresponding relation to the grip finger and push the rod cam assemblies and to this end, conveyor belts 293 that-are supported at one end by the shaft I28, Fig. '7, are extended to pulleys 294 that are mounted on an outer conveyor shaft 295. The ends of the conveyor shaft 295 are mounted in bearings 296 that are supported on substantially J-shaped brackets 291 and 298, the upper ends 299 of which are adjustably mounted in vertical ways 399 in the outer ends of the rails I5 and I6, as by the set screws or bolts 39I.

In order to correlate application of vacuum and atmospheric pressure to the operation of the grip fingers and push rod cams in such a mannet as not to impede release and stripping of work pieces from the silk screen frame, a piston type valve 392, Fig. 8, is interposed in the vacuum line 233-234 and actuated by a cam 393 on the drive shaft I89 for example. A spring pressed plunger 394 rides the cam 393 and acts on the valve 392 to start and stop vacuum action in the line 233234.

Suitable start-stop mechanisms 395 and 396, Fig. l, are also provided for actuating and deenergizing the compressor pump motor 49 and the gear box driving motor I98.

Operation The operation of a printing machine constructed as described is as follows:

A supply of work pieces is mounted on the feed tray table 49, Fig. 2, arranged at the right hand end of the machine relative to Fig. 1. The startstop mechanisms 395 and 396 are then operated to energize the motors, whereupon power is transmitted from the electric motor I98 to the gear box I96 and through the chain or belt I93 to the stub shaft I9I, Fig. 7. From the stub shaft I9I, power is transmitted through the chain I99 to the main drive shaft I89 and by a chain and sprocket mechanism 391, Fig. 7, to the line counter shaft 85. Power is also transmitted from the main drive shaft through a chain and sprocket comiection 398 to a stub shaft 399 and from the stub shaft 399 through a chain and sprocket assembly 3I9 to the feed belt roller WI. The line counter shaft 85 operates the cam shaft 18 through the belt connection 83. A chain and sprocket assembly 3| I extends from the feed belt roller I9I to the feed belt roller shaft I28 to operate the same. The stub shaft I9I drives the grip finger shaft 261 through the chain 269 and sprocket 268. The cam shafts 18, the conveyor belt shafts 96, I9I, I28 and 295, the stub shaft 399, the counter shaft 85, the main driveshaft I89, the stub shaft I9I and the grip finger shaft 261 all operate synchronously with the platen I21 rotating freely, and which platen, with the conveyor belt shafts IIII and I28 is vertically adjustable by the brackets I39, Fig. 6, to effect off-contact prints.

The cam shafts 18 move the suction cups M to feed work pieces as in Fig. 3 to the conveyor belts 98, Figs. 4 and '7, where the work pieces pass between the feed rollers 92 and I93, Fig. 4, and continue on in supported relation by the conveyor belts 98 or are ejected by the ejector mechanism tray I I1.

Passing the ejector tray I I1, the conveyor belts 98 pass the work pieces toward the platen, Fig. 5, but prior to reaching the platen, the silk screen frame 293 is moved to the right, Fig. 1, by the links 298, Fig. 9, rocker arms 299, throw arms 2I2, Fig. 1, and pitmans 2I4 which are actuated by the gear box I96. The length of throw of the screen frame 293 to the right is such as to cause abutment of the leading edge of the work pieces with the stop lugs 239, Figs. 9 and 10, on the screen frame end member 295, the bottom face of such work piece being engaged by the upper surfaces of the gripper fingers 239. As the work pieces cover the vacuum perforations back of the plate flange 229, Figs. 1 and 10, sufficient suction is provided to hold each work piece against the plate flange 229 to effect registry, alignment or securing of the work piece below the screen frame.

Continued movement of the pitmans 2I4 re ciprocates the throw arms 2I2 to move the screen frame to the left, Fig. 1, and thus deliver the work piece over the platen I21, Fig. 5, below the squeegee printing element I51. The cam I88, Fig.

1, is so arranged on the main drive shaft I89 as to lower the squeegee yoke synchronously with movement of the silk screen frame to the left, Fig. Ii Downward movement of the squeegee pivots the paint material trap to the right, Fig. l, and exposes the squeegee to paint and a silk screen that has previously been mounted on the frame 203. Continued motion of the screen frame to the left, Fig. 1, causes the squeegee to scrape paint over the silk screen and thus print the work pieces through a suitable stencil in the silk screen.

As the screen frame approaches the extremity of its stroketoward the left, Fig. l, the cams 266 and 216, Fig. 9, that are synchronously driven by the sprocket chain drive 269 act on the levers 25 1 and 214 to lift the floating bars 249 and 254 to rotate the arms 24'! and 253-and withdraw the grip fingers 239 and simultaneously push the rods 245 downwardly to strip the work piece from the screen frame and force it downwardly and outwardly relative tothe machine to deliver it to the conveyor'belts 293 at which time the work pieces may be collected and stacked in a suitable manner.

As the screen frame 203 completes its stroke to the left, Fig. I, and its direction of movement is reversed by the pitmans of the gear box acting on the throw arms, the cam I88 on the main drive shaft causes raising of thesqueegee frame yoke, whereupon the paint material trap is drawn to theleft, Fig. I, under the squeegee to prevent further supply of painting material. The operation just described may then be repeated at various speeds and lengths of stroke to successively act on and print the work pieces delivered to the conveyor from the feed tray.

Depending upon the type of material, the platen roller I21 with the conveyor shafts'llll' and i253 may be adjusted in the brackets l39- and the conveyor shaft 295 may be adjusted alongwiththe grip finger assembly to aid in stripping work pieces and removing the same from the silk screen frame. This latter adjustment of such assembly is effected by manipulation of the handle 290 and setting of the bolts 30! in the side rails l 5 and Hi.

It is also contemplated that pivotal movement of the latching dogs M9 for the squeegee assembly may be synchronously correlated, by a cam and shaft therefor, with rotation of the grip finger shaft, for example, to allow lowering of the squeegee when the screen frame starts its travel from right to left, Fig. 1, below the squeegee and to lock the squeegee yoke in raised position at the end of the right to left stroke of the silk screen frame to prevent application of painting material by the squeegee to the frame during the return stroke of the frame from left to right relative to Fig. 1.

While we have shown but one embodiment of our invention, it is apparent that the device is susceptible to modification without departing from the spirit of the invention. We do not wish, therefore, to be limited by the disclosures set forth, but only by the scope of the appended claims.

The invention described herein may be'manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim:

'1. In a printing machine, a support, a screen reciprocably mounted on the support, a printing element reciprocably mounted on the support, means for reciprocating said screen and printing element in cooperative relation, means for supplying the screen and printing element with printing material, a platen on the support cooperative with the screen and printing elements, means for feeding work pieces between the platen and screen, means interposed between the feeding means and platen for ejecting work pieces of predetermined character, means on the screen for clamping work pieces thereto, and means for stripping work pieces from the screen.

2. In a printing machine, a support, a screen horizontally reciprocably mounted on the support, means for controlling the length of stroke of reciprocation of the screen, a printing element vertically reciprocably mounted on the support, cooperative means for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, a work piece feed bed adjustably mounted on the support, means for successively removing work pieces from said bed, means for ejecting work pieces of predetermined character, a conveyor for receiving work pieces and leading the same to the platen, means on the screen for gripping work pieces presented thereto at one end of the reciprocating stroke. of the screen, means for causing cessation of operation of the machine upon misalignment of work pieces relative to the screen, means for stripping work pieces from the screen at the opposite end of the reciprocating stroke of the screen, and a conveyor synchronized with the first named conveyor leading from the platen to the delivery end of the machine opposite the Work piece feed bed.

3. In a printing machine, a support, a screen reciprocably mounted on the support, means for controlling the length of stroke of reciprocation of the screen, a printing element reciprocably mounted on the support, cooperative means. for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, a work piece feed bed mounted on the support, means for successively removing work pieces from said bed, a conveyor for receiving work pieces and leading the same to the platen, means for gripping work pieces presented thereto at one end of the reciprocating stroke of the screen, and means for stripping work pieces from the screen at the opposite end of the reciprocating stroke of the screen.

4. In a printing machine, a. support, a screen horizontally reciprocably mounted on the support, a printing element vertically reciprocably mounted on the. support, cooperative means for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, means for adjusting the platen relative to the screen and printing element, means for successively feeding work pieces to said platen, means for gripping work pieces presented to the screen, and means for stripping work pieces from the screen.

5. In a printing machine, a support, a screen horizontally reciprocably mounted on the support, means for controlling the length of stroke of reciprocation of the screen, a printing element vertically reciprocably mounted on the support, cooperative means for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, means for successively presenting work pieces to said platen, a conveyor for receiving work pieces and leading the same to the platen, means on the screen for gripping work pieces presented thereto, means for stripping work pieces from the screen, a conveyor synchronized with the first named conveyor leading from the platen to delivery end of the machine, and means for adjusting the platen and conveyors relative to the screen and platen.

6. In a printing machine, a support, a screen horizontally reciprocably mounted on the support, means for controlling the length of stroke of reciprocation of the screen, a printing element vertically reciprocably mounted on the support, cooperative means for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, means for successively presenting work pieces to said platen, a conveyor for receiving work pieces and leading the same to the platen, means on the screen for gripping work pieces presented thereto, means for stripping work pieces from the screen, a conveyor synchronized with the first named conveyor leading from the platen to delivery end of the machine, means for adjusting the platen and conveyors relative to the screen and platen, and means for adjusting one of the conveyors independently of the other of said conveyors.

7. In a printing machine, a support, a screen horizontally reciprocably mounted on the support, means for controlling the length of stroke of reciprocation of the screen, a printing element vertically reciprocably mounted on the support, cooperative means for reciprocating the screen and printing element in predetermined relation, a platen rotatably mounted on the support below the screen, a work piece feed bed adjustably mounted on the support, means for successively removing work pieces from said bed, means for ejecting work pieces of predetermined character, a conveyor for receiving work pieces and leading the same to the platen, means on the screen for gripping work pieces presented thereto at one end of the reciprocating stroke of the screen, means for causing cessation of operation of the machine upon misalignment of work pieces relative to the screen, means for strippin work pieces from the screen at the opposite end of the reciprocating stroke of the screen, a

conveyor synchronized with the first named conveyor leading from the platen to delivery end of the machine opposite the work piece feed bed, means for adjusting the platen and said conveyors relative to said platen and screen, and means for adjusting one of said conveyors and said stripping means independently of said platen and screen.

8. In a printing machine, a screen, a printing element mounted for oscillation toward and away from said screen, said screen being mounted for oscillation past said printing element durin contact of said printing element therewith, work feed means effective to convey work pieces into engagement with said screen, release means for freeing Work pieces from said screen, driving means, means connecting said screen to be oscillated by said drving means, means connecting said printing element to be oscillated by said driving means, means connecting said release means for actuation by said driving means, and adjusting means for varying the oscillation stroke of said screen.

9. In a printing machine, a frame adapted to hold a screen, a cylindrical platen disposed to roll against a screen in said frame, conveyor belt means adapted to convey work pieces into engagement with the screen in said frame, stop members on said frame adapted to engage the edge of work pieces as the latter are fed to said frame by said conveyor belt means, and suction means efiective to place individual work pieces on said conveyor belt means.

10. In a printing machine, a frame adapted to hold a screen, vacuum means adapted to hold a Work piece against said screen during, a printing operation, means for controlling the application of vacuum to said vacuum means, a release member effective to free a work piece from the screen. and means for synchronizing said vacuum controlling means and said release member.

11. A printing machine comprising a stencil frame reciprocable in a predetermined plane, a printing element movable to and from an oper ative position wherein it is in wiping contact with one surface of a stencil carried by said frame, means for actuating said frame and printing element in predetermined time relation, suction means carried by said frame for clamping a relatively rigid work piece to the other surface of the stencil, a rotatable platen positioned to contact the work piece opposite said printing element, and means carried by the stencil frame for stripping the work piece from the stencil after it has been printed.

12. The invention defined in claim 11, comprising in addition a feed bed for supporting a stack of work pieces, means for successively removin work pieces from said bed, means'for rejecting work pieces of predetermined dimensions, a conveyor for moving the unrejected work pieces into contact with the stencil, and means becoming operative upon misalignment of a work piece relative to the stencil for stopping the machine.

13. A printing machine comprising a stencil frame reciprocable in its own plane, suction means carried by said frame for holding a work piece in contact with a stencil carried by said frame during a printing operation, a push rod operable to free the work piece from the screen, and means synchronized with said push rod for rendering said suction means operative and inoperative.

ALMUS C. BARLOW. WILLIAM V. PAUL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date I 1,140,883 Dick May 25, 1915 1,341,402 Werney May 25, 1920 1,742,249 Hamlin Jan. 7, 1930 1,832,216 Johnston Nov. 17, 1931 1,901,473 Respess Mar. 14, 1933 1,922,341 Aldcroftt Aug. 15, 1933 2,060,385 Shurley Nov. 10, 1936 2,212,347 Lee Aug. 20, 1940 2,301,119 Holbrook Nov. 3, 1942 2,393,402 OGorman Jan. 22, 1946 2,393,614 Curtis Jan. 29, 1946 

